Exposure system

ABSTRACT

An exposure system is provided wherein a rotatable drum, having a support for an electrophotographic material, is rotatable past a series of processing stations and is connected by means of an endless belt to a carriage, which carriage is reciprocated back and forth across an exposure slit. This is accomplished by means, such as lugs or a clamp, which interlock the belt with the carriage in response to a predetermined position of the electrophotographic material to move the carriage across the exposure slit and thereafter disengage the carriage from the belt so that the carriage may be returned to its initial position by a return means for the next cycle.

United States Patent Hodges, deceased [451 Jan. 18, 1972 [54] EXPOSURE SYSTEM [72] Inventor: Howard T. Hodges, deceased, late of Perinton, N.Y. by Claire F. Hodges, executrix [73] Assignee: Eastman Kodak Company, Rochester,

[22] Filed: Sept. 26, 1969 [21] Appl.N0.: 861,511

[52] U.S.Cl ..355/8,355/48,355/50 [5i] 1nt.Cl. i ..G03g 15/00 [58] FieldofSearch .1 .355/3,8,81,84,47,48,49, 355/50, 51,25

[56] References Cited UNITED STATES PATENTS 1,977,188 10/1934 Kunz..... ..74/37 2,243,013 5/1941 Morey.. .74/37X 2,939,321 6/1960 Shovic.... ....74/37X 2,959,095 ll/l960 Magnusson ..355/11 X Primary Examiner-Samuel S. Matthews Assistant Examiner-Montoe H. Hayes AttorneyRobert W. Hampton and Gary D. Fields [5 7] ABSTRACT An exposure system is provided wherein a rotatable drum, having a support for an electrophotographic material, is rotatable past a series of processing stations and is connected by means of an endless belt to a carriage, which carriage is reciprocated back and forth across an exposure slit. This is accomplished by means, such as lugs or a clamp, which interlock the belt with the carriage in response to a predetermined position of the electrophotographic material to move the carriage across the exposure slit and thereafter disengage the carriage from the belt so that the carriage may be returned to its initial position by a return means for the next cycle.

7 Claims, 3 Drawing Figures PATEN-TED JMUBIQTZ FIG.3

HOWARD T. HODGES, DECEASED.

BY CLAIRE F. HODGES,EXECUTRIX INVENTOR 2 41 dual fiwn/da i ATTORNEYS sxsosnas SYSTEM CROSS-REFERENCE TO RELATED APPLICATION Reference is made to my commonly assigned copending US. application Ser. No. 777,717, filed Nov. 21, 1968, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an electrophotographic device and more particularly to a device wherein a carriage supporting an original document is reciprocated past an exposure slit in response to movement of a photoconductive surface past an exposure station, which station is one of a series of electrophotographic stations.

2. Description of the Prior Art It is common in the electrophotographic art to provide a rotatable drum as a support for an electrophotographic material, such as a photoconductor, which material is movable past a series of electrophotographic stations. As the drum rotates the photoconductor first moves past a charging station for placing a uniform electrostatic charge on the photoconductor. The photoconductor then moves past an exposure station where it is exposed to a radiation pattern, discharging exposed portions so that electrostatic image remains on the photoconductor. The photoconductor then passes through a toning or development station where toner particles are attracte d to the electrostatic image to form a visible image. This image may then be transferred to a suitable receiver sheet and the photoconductor may be cleaned, if desired, at another station for reuse. In such a system, it is necessary to move the original document to be copied in synchronism with the movement of the photoconductor so that successive portions of the photoconductive material may be exposed to the original document. Synchronism between the movement of the photoconductive material and the original document may be accomplished by means interconnecting a movable carriage for supporting the original document and the photoconductive support. This interconnection may take the form of belts which are endless, as disclosed in US. Pat. No. 2,959,095 to Magnusson, or may consist of belts which are wound up on pulleys, as in US. Pat. No. 3,062,094 to Mlayo. In each of these devices, the carriage is permanently attached to the belt and the belt is engaged or disengaged with a mechanism connected to the electrophotographic drum causing the belt and hence the carriage to move in synchronism therewith. Thus, a substantial load is placed on the drive mechanism whenever the belt is engaged because it is necessary to accelerate the mass of the entire drive system and the carriage. Such an arrangement can result in slippage at the beginning of the cycle so that in practice the carriage does not necessarily move in synchronism with the drum as desired. This can result in a misalignment or distortion of the resulting electrophotographic image.

BRIEF DESCRIPTION OF THE INVENTION In the present invention. a rotatably mounted electrophotographic drum or support is provided with a surface for supporting a photoconductor which is moved respectively through a charging station. an exposure station, a development station, a transfer station, and optionally through a Cleaning station. A carriage is movably supported for movement past an exposure slit so that an image may be projected by a lens system to the exposure station. An endless belt interconnects the electrophotographic support with the carriage so that the carriage moves past the slit at the same speed as the photoconductive material moves past the exposure station so that an electrostatic image may be formed thereon. The endless belt moves continuously with the drum but the carriage moves with the belt only during the exposure portion of the cycle. This is accomplished by means which releasably proaches the exposure station so that the carriage is moved with the belt across an exposure slit as the photoconductor moves across the exposure station. When the photoconductor has passed the exposure station, the carriage is disengaged from the belt so that the carriage may be moved back across the exposure slit to its initial position by return means, such as a weight or spring.

More particularly, in one embodiment an electromagnetic means, such as a solenoid, is provided for temporarily attaching the carriage to the belt. Just as the photoconductor is about to enter the exposure station, the photoconductor closes a switch in circuit with the solenoid causing the latter to grip the belt so that the carriage is moved therewith. At the end of the exposure cycle the switch is opened so that the solenoid releases the belt and the carriage is returned to its initial position, as by a weight. In another embodiment one ormore lugs are provided on the endless belt which engage the carriage at the beginning of the cycle to move it across the exposure slit and then become disengaged therefrom so that the carriage may be returned to its initial position.

Additional advantages of this invention will become apparent from the description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a diagrammatic side elevation, with certain parts in section for clarity of illustration, showing a preferred form of the invention wherein a solenoid is energized to grip an endless timing belt to move a carriage across an exposure slit;

FIG. 2 is a fragmentary perspective view of a portion of the electrophotographic support and shows the electrical circuit for the solenoid; and i FIG. 3 is a diagrammatic, fragmentary, side elevation of an alternative form of the invention in which lugs on the timing belt are engageable with the carriage to move it across the exposure slit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with this invention, an electrophotographic drum D is provided which is rotatably mounted about a shaft 10 and includes an electrophotographic transparent support, such as arcuate plate 11. The plate may be provided with an electrophotographic surface and, if desired, may extend the full circumference of the drum. In the embodiment shown, however, a photoconductor 12 is fed from the supply roll 13 across arcuate plate 11 to a takeup roll 14. Suitable means for advancing the material is shown in my commonly assigned copending US. application Ser. No. 777,717, filed Nov. 21, 1968, now abandoned. Conveniently, the drum may be driven by suitable drive means such as shaft 10, by a power source (not shown) in a counterclockwise direction, as indicated in FIG. I so that photoconductor l2 first moves past a charging station 15 so that a generally uniform electrostatic charge is placed on the photoconductive material. The photoconductor then moves past an exposure station so that the image projected by lens system 16 is projected onto the photoconductive material through the transparent support 11. In the exposed areas the electrostatic charge will be dissipated leaving a latent electrostatic charge image which may be developed by development station 17. A receiver or copy sheet is fed from a supply 18 by a suitable feed means 19 so as to be brought into face-to-face relationship with the photoconductor I2 at a transfer station 21. The transfer station may comprise a corona charger for placing a charge on the back surface of the copy sheet having a polarity opposite that of the toner particles so that they will be attracted to the copy sheet'This copy sheet can then be separated from the drum by a piclcoff means 22, fully described in commonly assigned copending US. application Ser. No. 861,508, filed on even date herewith. Then the copy sheet passes through a fusing station 23 so that the image can be fixed to the copy sheet. Any residual toner particles left on the photoconductor 12 can be removed therefrom connects the carriage and the belt as the photoconductor apat acleaning station 24.

A carriage C for supporting an original document such as document is mounted, as on rollers 26, for movement along a rail 27 so as to move the document past an exposure slit 28, illustrated as formed in the shield of a light source 29 whereby the original document is illuminated so that an image thereof is reflected by mirror 30 through lens system 16 and plate 11 onto photoconductive material 12 to form the latent electrostatic image. The original document 25 may be positioned upon a. transparent platen, such as platen 31 made of transparent material such as glass or plastic and is held in position by an opaque flexible cover 32 which conveniently is fixedly attached along one edge of the carriage. The carriage is normally held in the left-hand position, shown in dotted lines in FIG. 1 due to the force exerted thereon by weight 33 connected to one end of the platen by flexible cord 34 extending around a pulley 35. Any other suitable return means, such as a spring, could be used to move the carriage to the preexposure or left-hand position.

An endless drive means, such as endless belt 36, is provided for moving the carriage in response to movement of drum D which belt extends around the drum and around the pair of spaced pulleys 37 and 38 on opposite sides of exposure slit 28, as shown.

At the beginning of a cycle, the leading end of plate 11 moves photoconductor 12 past charging station 15. As it approaches the exposure station, a switch 39, which rides along a peripheral edge of plate 11, as best seen in FIG. 2, is closed completing a circuit to solenoid 44). Thus, a clamp, such as solenoid 40, is energized causing armature 41 to clamp or grip belt 36 to move carriage C along with the belt. The carriage may be constructed of relatively lightweight material so that the inertia to be overcome in accelerating it is relatively small. Thus, as photoconductor 12 moves past the exposure station at a particular angular velocity, carriage C is moved past the exposure slit at the same linear velocity so that an image reflected from the document on the carriage is projected onto a photoconductor to form a latent electrostatic image which is not distorted from the original image. This way, it can be seen that any long-term slip in belt 36 can be tolerated since the carriage and drum are resynchronized with each cycle. As the trailing end of plate 11 passes switch 39, the switch is opened as when the carriage reaches the solid line position shown in FIG. 1. This deenergizes solenoid 40 which releases belt 36 to permit weight 53 to pull the carriage back across slit 28 to the preexposure position while the drum continues to rotate, carrying photoconductor 12 through the other stations. The mechanism is arranged so that carriage C will be moved back to the left-hand position by the time the leading end of plate 11 reaches switch 39 again.

An alternative arrangement is shown in FIG. 3 wherein a belt 36' extending around spaced pulleys 37 and 38 is provided with spaced lugs 42 which engage corresponding spaced lugs 43 on carriage C causing the carriage to be moved past an exposure slit so that an image may be projected onto photoconductor 12. As the carriage reaches the right-hand position lug 42 rides off of lug 43 as that portion of belt 36' moves around pulley 38'. Once the lugs are disengaged the carriage may be returned to the left-hand position by suitable means, such as a weight or spring. If desired, belt 36 may be a timing belt to prevent slippage between it and the drum around which it extends.

From the foregoing, the advantages of this invention are readily apparent. A novel electrophotographic apparatus is provided wherein a carriage which is movable past an exposure slit is recycled with the movement of a photoconductive surface past an exposure station so that the angular speed of the photoconductive surface is the same as the linear speed of the carriage whereby a charged photoconductive surface is exposed to form a latent electrostatic image which is toned and transferred to a receiver sheet in a subsequent operation. in one embodiment electromagnetic means, such as a solenoid, is provided to grip an endless belt driven by the electrophotographic drum so that the carriage is moved past the exposure slit while the photoconductive surface is moved past an exposure station. The solenoid is deenergized as the photoconductor passes the end of the exposure station so that the carriage is returned to its initial position by a force exerting means such as a weight. in an alternative embodiment lugs are provided on the timing belt which engage lugs on a carriage, the lugs being appropriately spaced so that a lug is in carriage-engaging position just as the leading end of the photoconductor reaches the exposure station so that the carriage is moved across the expo sure slit in timed relation with the movement of the photoconductor. When the carriage has moved completely across the exposure slit the lug on the timing belt disengages with the lug on the carriage so that the carriage is free to be returned to its initial position.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

I claim:

1. In an electrophotographic apparatus including:

a support for a photoconductive member, said support being movable through a cycle along an endless path into and out of a series of operating stations, one of said stations being an exposure station;

means defining an exposure slit;

a document carriage movable along a path from an initial position past said exposure slit to a final position;

the improvement comprising:

drive means movable by said support for moving said carriage along said path in timed relationship with said support;

means on said carriage for releasably connecting said carriage to said drive means; and

means responsive to movement of said support into the exposure station to enable said connecting means at said initial position to connect said carriage to said drive means and responsive to movement of said support out of the exposure station to disable said connecting means at said final position to release said carriage from said drive means when said carriage reaches said final position.

2. In an electrophotographic device, as claimed in claim 1,

said improvement further including:

means for returning said carriage to said initial position.

3. An improvement as claimed in claim 1, wherein said connecting means includes a clamp on said carriage engageable with said endless drive means.

4. An improvement, as claimed in claim 3, wherein said clamp is electrically operated.

5. An improvement, as claimed in claim 1, wherein said enabling means includes:

spaced lugs along said endless drive means engageable with said connecting means on said carriage to move said car riage from said initial position past said exposure slit to said final position and separable from said connecting means upon reaching said final position.

6. An exposure device for an electrophotographic apparatus having a photoconductive element, said photoconductive element being movable along an endless path into and out of an exposure station for exposure to a document movable along a linear path from an initial position past an exposure slit to a final position, said device comprising:

means for supporting said photoconductive element for movement along said endless path;

a document support movable along said linear path from said initial position past said exposure slit to said final position;

an endless belt extending around said supporting means and mounted for movement along said linear path, said belt being releasably connectable to said document support along said path and being secured for movement by said supporting means upon rotation thereof to move said belt along said linear path;

means on said document support for releasably connecting said document support to said endless belt; and

means responsive to movement of said photoconductive element into said exposure station to enable said connecting means at said initial position to connect said endless belt to said document support for moving said document support past said exposure slit at substantially the same speed as said photoconductive element is moved past the exposure station and responsive to movement of said support out of the exposure station to disable said connecting means at said final position to release said support from said endless belt.

7. An exposure device for an electrophotographic apparatus wherein an original document is movable along a linear path to expose a photoconductive element to an image of the document as the photoconductive element is moved along a circular path into and out of an exposure station, said device comprising:

means defining an exposure slit;

a carriage for supporting an original document for move ment from an initial position along said linear path past said exposure slit to a final position;

a rotatably mounted drum having a peripheral surface which includes an arcuate plate for supporting the photoconductive element for movement along the circular path;

means for illuminating the original document as said carriage is moved along said linear path past said exposure slit;

means for projecting the image of said document onto the photoconductive element upon movement of the arcuate plate through the exposure station;

an endless belt extending around said peripheral surface of said drum, said belt being releasably connectable to said carriage along said linear path and being mounted for movement along said linear path in response to rotational movement of said drum;

means on said carriage for releasably connecting said carriage to said endless belt; and

means responsive to movement of said arcuate plate into the exposure station to enable said connecting means at said initial position to connect said endless belt to said carriage for moving said carriage along said linear path from said initial position past said exposure slit to said final position at the same speed as the photosensitive element is moved along said circular path through the exposure station to expose the photosensitive element to said image and responsive to movement of said arcuate plate out of the exposure station to disable said connecting means at said final position to release said carriage from said belt when said carriage is in said final position. 

1. In an electrophotographic apparatus including: a support for a photoconductive member, said support being movable through a cycle along an endless path into and out of a series of operating stations, one of said stations being an exposure station; means defining an exposure slit; a document carriage movable along a path from an initial position past said exposure slit to a final position; the improvement comprising: drive means movable by said support for moving said carriage along said path in timed relationship with said support; means on said carriage for releasably connecting said carriage to said drive means; and means responsive to movement of said support into the exposure station to enable said connecting means at said initial position to connect said carriage to said drive means and responsive to movement of said support out of the exposure station to disable said connecting means at said final position to release said carriage from said drive means when said carriage reaches said final position.
 2. In an electrophotographic device, as claimed in claim 1, said improvement further including: means for returning said carriage to said initial position.
 3. An improvement as claImed in claim 1, wherein said connecting means includes a clamp on said carriage engageable with said endless drive means.
 4. An improvement, as claimed in claim 3, wherein said clamp is electrically operated.
 5. An improvement, as claimed in claim 1, wherein said enabling means includes: spaced lugs along said endless drive means engageable with said connecting means on said carriage to move said carriage from said initial position past said exposure slit to said final position and separable from said connecting means upon reaching said final position.
 6. An exposure device for an electrophotographic apparatus having a photoconductive element, said photoconductive element being movable along an endless path into and out of an exposure station for exposure to a document movable along a linear path from an initial position past an exposure slit to a final position, said device comprising: means for supporting said photoconductive element for movement along said endless path; a document support movable along said linear path from said initial position past said exposure slit to said final position; an endless belt extending around said supporting means and mounted for movement along said linear path, said belt being releasably connectable to said document support along said path and being secured for movement by said supporting means upon rotation thereof to move said belt along said linear path; means on said document support for releasably connecting said document support to said endless belt; and means responsive to movement of said photoconductive element into said exposure station to enable said connecting means at said initial position to connect said endless belt to said document support for moving said document support past said exposure slit at substantially the same speed as said photoconductive element is moved past the exposure station and responsive to movement of said support out of the exposure station to disable said connecting means at said final position to release said support from said endless belt.
 7. An exposure device for an electrophotographic apparatus wherein an original document is movable along a linear path to expose a photoconductive element to an image of the document as the photoconductive element is moved along a circular path into and out of an exposure station, said device comprising: means defining an exposure slit; a carriage for supporting an original document for movement from an initial position along said linear path past said exposure slit to a final position; a rotatably mounted drum having a peripheral surface which includes an arcuate plate for supporting the photoconductive element for movement along the circular path; means for illuminating the original document as said carriage is moved along said linear path past said exposure slit; means for projecting the image of said document onto the photoconductive element upon movement of the arcuate plate through the exposure station; an endless belt extending around said peripheral surface of said drum, said belt being releasably connectable to said carriage along said linear path and being mounted for movement along said linear path in response to rotational movement of said drum; means on said carriage for releasably connecting said carriage to said endless belt; and means responsive to movement of said arcuate plate into the exposure station to enable said connecting means at said initial position to connect said endless belt to said carriage for moving said carriage along said linear path from said initial position past said exposure slit to said final position at the same speed as the photosensitive element is moved along said circular path through the exposure station to expose the photosensitive element to said image and responsive to movement of said arcuate plate out of the exposure station to disable said connecting means at said final position to release said carriage from said belt when said carriage is in said final position. 